Objective To assess the value of dual-source computed tomography angiography (DSCTA)in detecting intracranial aneurysms by comparing with conventional and three-dimensional DSA.Methods In this study,95 patients with subarachnoid hemorrhage(SAH)underwent both DSCTA and DSA examination.The detection rate,size,and ratio of the neck to the dome(N/D ratio)of the aneurysrns were evaluated.Statistical analysis was performed using a paired sample Student's t-test for the comparisons of the value of N/D and 2 Related Samples test for long axis.Results A total of 67 aneurysms in 63 patients at DSA and 64 aneurysms in 60 patients at DSCTA were detected,respectively;whereas no aneurysm was detected in 32 patients at DSA.Compared with DSA,the overall sensitivity.specificity,positive predictive value,and negative predictive value of DSCTA on a per-aneurysm basis were 94.2%,100.0%,100.0%,and 91.4%,respectively.For the aneurysms larger than 3 mm,the sensitivity and specificity of DSCTA in detecting intracranial aneurysms were equal to those of DSA:For aneurysms smaller than 3 mm,however,the sensitivity and specificity of DSCTA is 80.0% and 100.0%.The N/D ratio for DSA and DSC:TA was 0.46±0.14 and 0.51±0.18.respectively,and the median of long axis was 4.9 mm and 4.8 mm.respectively.There was no significant difierence in the N/D ratio(t=3.20;P＞0.05)and the long axis(Z=-1.309;P＞0.05)between DSA and DSCT.Condusions Compared with conventional and three-dimensional digital subtraction angiography,DSCTA has high sensitivity and specificity in the detection of intracranial aneurysms,especially for detection of snlall aneurysnm(＜3 mm).It can be used as a routine screening technique.

Objective To improve diagnosis accuracy of pineocytoma (PC) by joint analysis of CT,MRI imaging features and differential diagnosis with other lesions in pineal region.Methods Totally 6 pineocytoma patients confirmed surgically and pathologically had their clinical history,CT and MRI data collected and analyzed on lesion morphology,cystic solid changes,existence of necrosis,complications of hemorrhage and or calcification,MRI and enhanced scan of solid component,complications with hydrocephalus and etc.Results Plain scan found 1 case of solid nodule and 5 cases of cystic-solid nodules,2 cases with clearly-bordered lesions and 4 one not as well as 4 cases with significant hydrocephalus and 2 ones with light hydrocephalus.Enhanced scan showed 5 cases of moderate to marked enhancement and one case with no obvious enhancement.CT examination proved there were 1 case of calcification and 1 case of hemorrhage.Conclusion Pineocytoma has the characteristics of benign tumor,and has to be differentiated with other tumors frequently occurring in this region in case of obvious clinical signs due to crushing brain parenchyma or blocking aqueduct cerebri by oversized lesions.

ObjectiveTo evaluate the image quality of displaying the pulmonary artery and pulmonary emboli at different tube voltages and find the optimal tube voltage.MethodsSixty-six patients underwent contrast-enhanced dual energy CT pulmonary angiography (CTPA) from August 2007 to February 2010.Data obtained with 80 kVp,weighted average 120 kVp,and 140 kVp were divided into group Ⅰ,Ⅱ,and Ⅲ respectively.CT value of pulmonary artery ( grade 1—4),emboli,and muscles were measured.Corresponding signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated.One-way ANOVA analysis and Friedman test were used to analyze statistical significance among these values.Image quality of CTPA from these three groups was assessed.The inter-reader agreement of image quality was performed by kappa test.ResultsCT value of branch 1 to 4 of ptlmonary artery was (446 ± 140) HU,(433±130) HU,(411 ±138) HU,and (392±127) HU in group Ⅰ,(303±91) HU,(290±85) HU,(276±86) HU,and (263 ±85) HU in group Ⅱ,and (244 ±70) HU,(230 ±63) HU,(216 ±72) HU,and (205 ±68) HU in group Ⅲ.There was significant difference for CT values (P ＜0.01) among three groups.CT value of pulmonary artery in 80 kVp images was higher than 140 kyp and 120 Kvp.On quantitative analysis of 37 patients,CNR value of pulmonary clots was 8.3 ± 3.3,8.0 ± 2.9,and 5.6 ± 2.2 in group Ⅰ,Ⅱ,and ⅢⅢ,respectively.CNR values of pulmonary clots in 80 kVp images and 120 kVp images were higher than that in 140 kVp (P ＜0.01 ).There was no statistical difference for image quality of CTPA among the three groups ( P ＞ 0.05 ).Agreement of image quality of CTPA derived from 80 kVp (kappa value =0.789,P ＜0.01 ) was superior to that of 120 kVp (kappa value =0.652,P ＜0.01 ) and 140 kVp ( kappa value = 0.509,P ＜ 0.01 ).Conclusions CT value of pulmonary artery in 80 kVp images was higher than that of weighted average 120 kVp and 140 kVp,and the image quality and CNR was comparable with that of weighted average 120 kVp images.This tube voltage ( 80 kVp) is optimal for CT pulmonary angiography in the evaluation of patients with suspected pulmonary embolism.

Objective To evaluate monoenergetic imaging of dual energy CT in the visualization of metal fixation of factures. Methods In total, 29 patients with factures underwent 36 metal fixations,including 11 external fixations implanting in tibiofibula (n = 11 ) and 25 internal fixations (cervical spine,n=10; lumbar spine, n=4; tibiofibula, n=8; radial bone, n=3). They were recruited into this study.After dual energy CT scan, monoenergetic software was used to post-process with the following 6 photon energies: 40, 70, 100, 130, 160, 190 keV. Two radiologists evaluated and rated the reformatted images with 6 different photon energies and average weighted 120 kV images according to the following 4-score scale. Score 1: nonassessable, with marked artifact; score 2: assessable, moderate artifact; score 3: good,mild artifact, good visualization of bony structures; score 4: excellent, no artifact. Kruskal-Wallis was used to perform statistical analysis of image quality for total fixations, external and internal fixations with various selective kev settings and average weighted 120 kV. Results For total fixations, monoenergetic imaging of dual energy CT has 25 fixations with score 3 and 4, but 120 kV has only 4 fixations with score 3 and 4.Monoenergetic imaging of dual energy CT improved image quality of fractures with metal fixation compared to average weighted 120 kV images ( F = 116. 487, P ＜0. 01 ). Images of 130 kev had the best image quality for external metal fixation (9 fixations with score 3 and 4, F = 60. 902, P ＜ 0. 01), while 70 kev was best for internal metal fixation ( F = 122. 149, P ＜ 0. 01). Conclusions Monoenergetic imaging of dual energy CT improves image quality of fractures with metal fixation. Reformatted images at 70 keV and 130 keV havethe optimal image quality for internal and external metal fixation, respectively.

Objective To discuss the value of digital tomosynthesis for detection of pulmonary nodules. Methods Thirty patients suspected of having pulmonary nodules underwent chest radiography, digital tomosynthesis and CT examination. Above image data were transferred to postprocessing work station and were reviewed by 2 radiologists with 3 years of chest-radiology diagnosis experience in a double-blind method. The number, location and size of nodules were recorded. Then, 2 radiologists reviewed the all images once more, and discuss in consensus. The sensitivities of chest radiography and digital tomosynthesis for detection of pulmonary nodules were respectively calculated according to the CT results. Chi-square test was used for radiography, digital tomosynthesis and CT examination. Results Of 30 patients, 21 were detected having pulmonary nodules by X-ray radiography and 9 were negative, the total number of 40 nodules was detected, while 89 nodules in 26 patients were detected by digital tomosynthesis, and only 4 patients were negative. CT demonstrated 102 nodules in 27 patients, and 3 patients were negative. Taking CT as "gold standard", the sensitivities of X-ray radiography and digital tomosynthesis were 27.4%(28/102)and 87.2%(89/102), X~2=4.35, P<0.05, respectively. Conclusion Digital tomosynthesis has a high sensitivity for detection of pulmonary nodules compared with X-ray radiography, and could be an excellent and necessary supplementary technique of X-ray radiography.

clues for interpretation of myocardial ischemia.

Objective To evaluate the clinical values of dual energy lung perfusion using dual-source CT. Methods Fifty-four patients who underwent chest contrast-enhanced CT were included in this study from May to August in 2007. Dual energy CT scanning was performed in all patients. The patients were divided into four groups: normal group, exudation lesion group, mass lesion group, and pulmonary embolism group. Imaging appearances of dual energy CT perfusion in four groups were analyzed. Results Dual energy CT showed symmetrical homogeneous perfusion in healthy subjects (n = 14), exudation lesions (n =10) appeared as low perfusion, In mass lesions (n =27), peripheral masses presented as local perfusion defect, central masses appeared as segmental perfusion defect because of the involvement of hilar vessels,and pulmonary embolism (n = 3) appeared as perfusion defect in corresponding pulmonary segment.Conclusion Dual energy CT scanning can be used to show the pulmonary perfusion status and assess the pulmonary perfusion abnormalities in central lung cancer and pulmonary embolism.

Objective To establish the animal model of chronic thromboembolic pulmonary hypertension(CTEPH) and to compare the accuracy of dual-energy CT (DECT) pulmonary angiography and histopathology for detecting CTEPH. Methods Eighteen canines were included in the study. All canines underwent paracentesis, embolization, CT scanning, pressure measurement and tranexamic acid feeding. The procedures were repeated every two weeks, until systolic/diastolic pressure in canines was≥30/15 mmHg or mean pulmonary artery pressure ≥ 20 mmHg.And then canines were sacrificed for histopathology examination. For CT pulmonary angiography (CTPA)in DE mode and DECT lung perfused blood volume (Lung PBV) images, the presence or absence of PE or perfusion defects were recorded on a per-canineand aper-lobe basis. With histopathological results as reference standard, the sensitivity, specificity of CTPA and lung PBV to detect PE were computed for two readers. The pairedχ2 test (McNemar test) was used to analyze the difference in diagnostic accuracy between CTPA and Lung PBV. Inter-reader agreement was also calculated with kappa test. Results CTEPH was demonstrated in 13 canines. On a per-canine basis, both readers found uneven and peripheral perfusion defects with DECT in 11 canines (84.6%, 11/13); while 5 canines (38.5%, 5/13) had cutoff or sudden stenosis of pulmonary arteries with CTPA;on a per-lobe basis,
both readers had sensitivities of 14.3%(5/35), 83.3%(30/36), specificities of 100.0%(30/30), 100.0%(29/29), accuracies of 53.8%(35/65), 90.8%(59/65)for CTPA and DECT, respectively. DECT had a higher sensitivity(χ2=-4.690,P<0.01)and accuracy(χ2=8.284,P<0.01) in detecting CTEPH. Excellent and moderate inter-reader agreements were observed with CTPA and DECT (Kappa=0.938, 0.572, both P<0.001). Conclusions It is feasible to make a CTEPH animal model with autologous thrombus. DECT shows a higher accuracy than CTPA to detect CTEPH in this canine model study.

Objective To explore the clinical value of dual-energy CT lung perfusion imaging and perfusion scintigraphy in acute pulmonary embolism (PE) rabbit models. Methods Acute PE models were established in 20 rabbits with femoral vein injection of sponge as embolus materials, and 4 rabbits were injected saline as control group. Two hours after embolization, dual-energy CT and perfusion scintigraphy imaging were performed respectively. Taking the pathologicall findings as the reference standards, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of both imaging methods were compared. CT values and enhancement degree (overlay value) of the embolic areas and normal pulmonary parenchyma were measured in DEPI image after embolization. Results Normal lung was color-coded as homogeneously yellowish red, perfusion scintigraphy displayed rarefaction or absence. The sensitivity, specificity, PPV, NPV of DEPI was 100%, 97.50%, 95.24%, 100%, and of perfusion scintigraphy was 67.50%, 81.25%, 64.29%, 83.33%, respectively. Increased CT values and overlay values of embolism areas in DEPI images were lower than those of normal pulmonary parenchyma (P<0.05). Conclusion DEPI has higher sensitivity and specificity than perfusion scintigraphy for detection of pulmonary emboli in an acute PE rabbit models.

Objective To evaluate the diagnostic accuracy of digital subtraction bone removal CT angiography (DS-BR-CTA) and dual energy bone removal CTA (DE-CTA) compared with conventional and rotational DSA. Methods A total of 264 patients underwent 3D-DSA were enrolled, 190 of them underwent also DS-BR-CTA, while 74 underwent DE-CTA as well. Aneurysms detected with DS-BR-CTA and DE-CTA were analyzed compared with 3D-DSA on per-patient and per-aneurysm basis. The sensitivity, specificity, positive predictive value and negative predictive value of two methods for diagnosis of aneurysm were calculated. Results Taking DSA as the standard, the sensitivity and specificity of DS-BR-CTA to detect intracranial aneurysms was 96.90％ and 98.36％ on per-patient basis, while 97.37％ and 99.97％ on per-aneurysm basis, and the sensitivity and specificity for the detection of aneurysm ≤3 mm was 88.89% and 98.36%. The sensitivity and specificity of DS-BR-CTA to detect intracranial aneurysms was 98.25% and 100% on per-patient basis, 95.52% and 100% on per-aneurysm basis, and the sensitivity and specificity for the detection of aneurysm ≤3 mm was 90.91% and 100%. Conclusion DE-CTA has a comparable diagnostic accuracy with DS-BR-CTA to diagnose intracranial aneurysms, and can be used in the routine workflow for detection of intracranial aneurysms.